cooling fan 94 lx

[ti1070]

I have read a few posts but they all deal with cars with AC, so I can't get a direct answer. Cooling fan will not kick on. If I unplug the temp sensor the fan runs constantly. Not a problem, but that check engine light stays on with a fast idle. Is there a way to tell if it is the temp sensor or a relay that is bad? The coolant level is fine and everything seems to be working fine. The only other thing is the seat belt fuse is out, but I don't think the two are related. Thanks for any help.

[A. Souphound]

Originally Posted by ti1070

I have read a few posts but they all deal with cars with AC, so I can't get a direct answer. Cooling fan will not kick on. If I unplug the temp sensor the fan runs constantly. Not a problem, but that check engine light stays on with a fast idle. Is there a way to tell if it is the temp sensor or a relay that is bad? The coolant level is fine and everything seems to be working fine. The only other thing is the seat belt fuse is out, but I don't think the two are related. Thanks for any help.

With a CEL on, you should extract the trouble codes.

The PCM turns the cooling fan/s on when the ECT sensor signals the coolant is above approx. 200F. When you unplugged the ECT connector,
no voltage signal was sent to the PCM. This 'fools' the PCM into thinking the coolant is above 240F.....and the fan/s came on indicating the fan relay circuit is in tact. Do you see any difference in the Temperature Indicator reading higher or lower than normal? If you do, my conclusion would be the ECT sensor is defective.

Seat Belt fuse blown: Passive Restraint system has two fuses....a 30A for the 'belt' and a 15A 'meter' fuse. Check both of them. If you have a DVOM/VOM or trouble light, those circuits can be checked for the apparent 'short' that blew the fuse.

[ti1070]

Originally Posted by A. Souphound

With a CEL on, you should extract the trouble codes.

The PCM turns the cooling fan/s on when the ECT sensor signals the coolant is above approx. 200F. When you unplugged the ECT connector,
no voltage signal was sent to the PCM. This 'fools' the PCM into thinking the coolant is above 240F.....and the fan/s came on indicating the fan relay circuit is in tact. Do you see any difference in the Temperature Indicator reading higher or lower than normal? If you do, my conclusion would be the ECT sensor is defective.

Seat Belt fuse blown: Passive Restraint system has two fuses....a 30A for the 'belt' and a 15A 'meter' fuse. Check both of them. If you have a DVOM/VOM or trouble light, those circuits can be checked for the apparent 'short' that blew the fuse.

Yes the car is running hotter. When I unplugged the ECT I did it each time with a relay in my hand. All three had clicked which is my assumption that the ECT is bad also. Off to the parts store to give it a try. Thanks.

[94scort]

How did this work for you? My car and my brother in law's car have the same problem. The fan does not kick on at low speed, but will kick on at high speed once the temp is way up.
The low speed works as the fan clearly turns on when the car is first started and both speeds work when a code reader is hooked up to it... so it is not the relays and is not the fan motor.
I just don't know whether to suspect the collant sensor or the computer, and don't know how to test either withtout simply replacing them.